Denoms are 12 and 18
12=2*2*3
18=2*3*3
lcd=2*2*3*3=36
lcd=36
6.70 for paint brushes. for 2 is 6.70×2=$13.40
35-13.40=$21.60 left after 2 paint brushes
4.80×4=$19.20 for 4 tubes of paint
21.60-19.20=$2.40 left after 4 tubes of paint and 2 paint brushes
Hey!
Let's write it,

Add

to both sides,


Subtract

from both sides.


Since we don't want a negative variable, we have to divide both sides by

.

Our answer would be,

Thanks!
-TetraFish
Consider inequality
This inequality is equivalent to inequality 
This means that 
The greatest integer number n, such that
when dividing by 7 gives the remainder 4 is 39. Then subtract 7, you get 32, then 25 and so on.
When n=-39, -32, -25, -18, -11, -4, 4, 11, 18, 25, 32, 39 then dividing by 7 the remainder is 4.
Answer: 12 integers.